Molds

Looks like I'm going to have to try sand casting these. The plaster outgasses something terrible when the hot bismuth is added disturbing crystal formation. My first couple of attempts all ended with a very thick rough inner surface and maybe the edge of a crystal.
I have also spent a whopping 4.50 on a box of borax to use for flux. I think this might cut down on the grey scum oxide layers formation.


Olivine sand and bentonite clay....

Busy Busy

I have managed to destroy 1/2 dozen eggs, and made quite a mess. But I now have 2 molds. A very basic half round, and a 2 piece full egg. I made the molds out of plaster of paris which burns at 1200F since the bismuth will be poured around 700, they should hold up for awhile. I will use the half round to test things. I suspect I need to preheat the molds for best crystal growth. Slower cooling = larger crystals. I was worried about a good mold release, ideally carbon based. I remembered a solution and just sooted the mold with a lighter. We will see how well that works.
I'm going to the supply store to pick up some safety equipment Monday, I don't feel like getting burned.
Later in the week I will start melting (fingers crossed) and growing crystals.

Modeling clay and a wax cast egg.

 I embedded the wax model egg halfway into a slice of modeling clay and built up a back from there that fit nicely when wedged into a stainless steel bowl.

Wax egg and a poured plaster half.

 I wedged the clay face in the bowl and added some supports. I needed more supports plaster is heavy when wet.

Finished mold with the opening to pour the excess out of.

Once I had 1 half the other half was simple.

Simple simple

I poured some plaster and stuck one of my wax eggs into it.

Well I have the bismuth sitting here, and have been working on egg molds. I've been trying to do it in a half-assed manner and surprise surprise, I've learned several important lessons in what not to do.

Getting the positive image of the egg in paraffin has proven easy. Well easy since I'm not after a whole egg my vision is a little different. I'm not positive if cutting the top off or cutting an angel off will work better so I'm trying both. 

Getting the halfway mark on the egg has proven a little more challenging

I'm going to have to break down and get some modeling clay, and possibly some RTV. In the meantime I'm waiting for the IR thermometer to arrive.